Im making a Cheshire cosplay (DC not the cheshire cat ;3 ) and on my mock ups i'm having trouble getting it to fit my figure when sewing...Because of the style of the dress tight in the waist and loose in the skirt area. Would adding corset holes (or whatever the fixtures are called, my mind is going blank) work on a satin silk fabric? Or would it be just easier to make the dress a separate top and bottom for a dress? My measurements are weird so its hard to make it work.. Heres the reference photo.

Not sure what you mean 'loose in the skirt'. It looks like a fitted mini-dress that is snug in the skirt, just with slits at the thigh.

Lacing holes only work if you're also going to be putting in structure like a corset, i.e. boning. Without this structure, the tension of lacing will make the whole thing collapse vertically and wrinkle.

Find a pattern for a fitted mini-dress and go from there.
Or, alternatively, if you prefer, make a fitted miniskirt and separate blouse. To fit the blouse at the waist, use darts and adjust the seams as needed. To keep the blouse from coming untucked I'd recommend building it with a leotard bottom; that would also protect you from panty flashes with a skirt that short.